In the methods of processing waste cooking oil proposed in Japanese patent laid open publications Nos. 60-44597 and 59-81398, waste cooking oil is absorbed into inorganic non water soluble substances such as activated clay, montmorillonite, sepiolite, bentonite, calcite, attapulgite, clay and so on and is then filtered for reuse. According to other known methods of processing waste cooking oil, enzyme may be applied to the waste cooking oil, or the waste cooking oil may be chemically reduced or absorbed into fibril media such as paper, non-woven fabric, rayon fibers and so on.
Japanese patent laid open publication No. 55-106298 discloses a method in which waste cooking oil is solidified by means of a certain higher fatty acid to form a gel which can be readily disposed of.
In the above mentioned prior art methods of processing waste cooking oil, since the waste cooking oil is either recycled in a form which may not be suitable for human consumption or is simply discarded, it cannot be fully utilized. There is therefore a demand for a method or a substance which will allow waste cooking oil to be recycled in the form of a reuseable substance.
It has been known previously that soap can be produced as a result of a (saponification) reaction between alkali metal hydroxide such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, etc. or sodium orthosilicate (as proposed in Japanese patent laid open publication No. 61-116000), which is also highly alkaline, and animal fat or vegetable oil. However, such strong alkaline chemical compounds are not suitable for use at home. Alkali metal hydroxide is highly reactive with carbon dioxide and humidity in the air and could be dangerous because the reactions are often extremely violent.